Technical Field
The present disclosure is directed to electrostatic discharge protection for a smart card reader.
Description of the Related Art
A smart card, also known as a chip card or an integrated circuit card, refers to a card that houses an embedded circuit capable of providing various applications, such as identification, authentication, and data storage. Signals of the embedded circuit are brought to a surface of the smart card by electrically coupling the embedded circuit to a number of contact pads on the surface of the smart card. Most smart cards have eight contact pads. Generally, six of the contact pads are defined: VCC, GND, Reset, Clock, Vpp, and Serial Data I/O, while two are reserved for future use.
A smart card reader includes a number of terminals electrically coupled to internal circuitry of a housing. When a smart card is fully inserted in to the smart card reader, the terminals contact the contact pads of the smart card, and, as a result, electrically couple the internal circuitry of the housing to the embedded circuit of the smart card.
Smart cards and set top box circuitry coupled to smart card readers are particularly vulnerable to electrostatic discharge. Smart cards are generally made of plastic, and, as is known, electrostatic charge can accumulate on plastic. For example, if a person walks on carpet and then handles a smart card, an electric charge may accumulate on the plastic portions of the smart card. Consequently, when the smart card is inserted in to the smart card reader and comes into contact with the terminals of the smart card reader, an electric arc may occur and damage the embedded circuit of the smart card and internal circuitry of the housing. As such, electrostatic discharge protection is needed to prevent damage to the embedded circuit of the smart card and the internal circuitry of the housing. Current methods typically utilize standard circuits, such as diodes and capacitors, to discharge an electrostatic charge. However, such methods are costly because an individual electrostatic discharge circuit is needed for each terminal of the smart card reader. Further, it is contemplated that smart cards that require more than the conventional eight contact pads will eventually be employed. As the number of smart card contact pads increases from eight to twelve, for example, adding a custom, dedicated electrostatic discharge protection circuit for each terminal of a smart card reader becomes costly and impractical.